1. Technical Field
The present invention relates to a lighting unit for a vehicle in which a light emitting unit such as a light emitting diode is used as a light source.
2. Related Art
In recent years, there have been employed a large number of related art lighting units for a vehicle in which a light emitting diode is used as a light source.
For the foregoing related art, Japanese publication JP-A-2002-50214 discloses a lighting unit for a vehicle comprising a light emitting diode provided toward the front part of the lighting unit and a light transmitting member provided on the forward side of the light emitting diode.
The related art lighting unit is constituted to lead a light emitted from the light emitting diode and incident on the rear end of the light transmitting member to the front end face of the light transmitting member and to emit the light from the front end face, and further, to irradiate the light onto the forward part of the lighting unit through a projection lens provided in front thereof.
In the lighting unit for a vehicle described in JP-A-2002-50214, a light emitted from the light transmitting member is refracted in such a direction as to separate from the optical axis of the projection lens on the front end face of the light transmitting member. Therefore, the rate of the light incident on the projection lens is decreased. Consequently, there is a related art problem in that a luminous flux utilization rate for a light emitted from the light emitting diode is not very high.